(char*)0
.
It is allowed to copy the data and use PL_recorded_external() on the copy. The user is responsible for the memory management of the copy. After copying, the original may be discarded using PL_erase_external().
PL_record_external() will fail if the term contains blobs that cannot be serialized, such as streams.
PL_recorded_external() is used to copy such recorded terms back to the Prolog stack.